"It may be that the sanctions screw needs to be or can be turned here and there," Guttenberg told reporters at the annual Munich Security Conference on Sunday, January 7. "We need to consider very carefully what impact our options could have."
"At the same time, however, it must be made clear to Iran that our patience is at an end."
He was speaking after Iranian President Mahmoud Ahmadinejad said his country would soon start enriching uranium to 20 percent on its own.
"We are still interested in cooperation [with the West] but if they want to continue playing games with the Iranian nation, then we will be prepared to do the 20 percent by ourselves," Ahmadinejad said at a laser technology conference in Tehran on Sunday.
The president of the Islamic nation said the Iranian Atomic Organization (IAO) was ready to begin the uranium enrichment and would eventually do so.
"I have given [world powers] a time range of two to three months to accept the deal but if they don't, we would start ourselves," he said.
"Now Dr [Ali Akbar] Salehi, should start to make the 20 percent with the centrifuges," the president said, addressing Iran's nuclear chief who was sitting in the audience at a laser technology plant in Tehran.
Later, Iran's Arabic-language television station al Alam quoted Salehi as saying Iran would formally inform the Vienna-based United Nations nuclear watchdog, the International Atomic Energy Agency (IAEA), about the move in a letter on Monday. He said production would take place at the Natanz enrichment facility in central Iran.
State media also quoted Salehi as saying that Iran plans to build 10 new uranium enrichment facilities during the next year.
Last year, the IAEA proposed that Iran ship low-intensity uranium abroad for enrichment, then re-import the enriched variant for use in a medical reactor, used to treat cancer patients, in Tehran.
The idea was to give Iran access to peaceful nuclear technology without it enriching uranium at home and so allay fears held by world powers that Iran might try to produce a nuclear bomb.
After months of stalling, Ahmadinejad said last week said that his country was willing to accept the deal.
Western officials at the Munich conference on Saturday criticized Iran, however, for not submitting a concrete plan for uranium exchange, and accused Tehran of pursuing a secret program to manufacture an atomic bomb.
German Foreign Minister Guido Westerwelle said that Iran still had to prove to the rest of the world that it was willing to make meaningful concessions regarding its nuclear program.
"Our hand is still reaching out towards [Iran]," Westerwelle said. "But so far it's reaching out into a void. And I've seen nothing since yesterday that makes me want to change that view."
Iran's Foreign Minister Manouchehr Mottaki met with IAEA head Yukiya Amano on Saturday in Munich. Amano said the Iranians brought nothing new to the table.
"We had a very interesting discussion," Amano said. "There was not a new proposal."
Foreign Ministry spokesman for the Islamic Republic, Ramin Mehmanparast, said on Sunday that remarks by Western officials in Munich had complicated the issue of uranium exchange.
He said comments suggesting that Iran should not have nuclear weapons were irrelevant to the main issue, which was to implement a deal based on an initiative by the IAEA, which, he said, should not be a "political propaganda" forum.
"Raising the irrelevant issue of nuclear weapons which have never been in our military doctrine, [the world powers] have just further complicated the issue," Mehmanparast said.
"Iran is still ready to make the deal and whenever the other side is ready as well, the technical negotiations by the experts could start," the spokesman added.
Editor: Chuck Penfold